Chicken parasite? Worm type thing? HELP!

Alright, so I'm newer to chickens. I started with chicks and they still aren't laying yet. We recently cleaned out their tractor and removed the duck, which has helped keep it cleaner (removing the duck I mean). I was letting them out this morning and pet one then noticed a bunch of tiny worm like things crawling on my hand. They were small and dark and definately moving! What are they, are they harmful? How do I get rid of them?

They aren't maggots. I have tried looking it up and haven't found anything yet. I treated them with Seven dust and put more sand in their coops for them to "bathe" themselves. I also added ACV to their water so if it is a parasite it will help them! Tomorrow they are getting vitamins too...

How small are they? If they're super-duper-itty-bittie-teenie-tiny, I'd assume mites or lice... Definitely dust them in either Diatomaceous Earth, plain 'ol firepit ash, or a commercial insecticide powder; I use DE constantly for poultry mite management as well as any worm any of my critters can get. I even killed flea infestations on some rescue rabbits with the stuff, it's amazing.